In the oil drilling industry, bit balling refers to a buildup of cuttings from clay (also known as shale) that may adhere to a drill bit. Drill “cuttings” are broken bits of solid materials produced as rock or soil is broken apart that must be continuously removed from the borehole during drilling. Bit balling may occur at almost any time, and may result in a reduction in the rate of penetration, reduced surface torque of the drill bit, and an increase in stand pipe pressure. As clay accumulates and bit balling increases, drilling will slow and, eventually, may have to be stopped for the drill bit to be cleaned.
Conventional additives or coatings may be used to control bit balling tendencies; however, most additives require an oil phase in the drilling fluid or require an emulsified drilling fluid to be effective. The oil phase in the fluid may provide lubrication necessary for the additives to function. Some anti-bit balling additives also require a particular pH range and cloud point range to be compatible with the drilling fluids used. Additionally, the efficacy of conventional additives and coatings is lacking, often requiring the drill to be frequently removed and cleaned before drilling can proceed.